A failure criterion of crack-containing plate under impact loading

The problem of dynamic initiation for crack-containing plate of I-mode under low-velocity impact load is investigated. The tangential strain of crack tip plastic zone is analysed and a calculation model of crack tip is set up by using the pattern of crack tip plastic flow. Then a relationship is established between CTOD and maximum tangential strain on the circumference of the crack tip plastic zone. According to the analysis, a dynamic initiation fracture criterion-maximum tangential strain theory is put forward. The impact tensile tests of the crack-containing LY-12CZ specimen are carried out on the MTS-810 machine. Using numerical computation-experimental method, the curves relating (t), CTOD (t) and J_d(t) to time t are calculated. Thereby the effectiveness of the maximum tangential strain theory as dynamic initiation criterion is proved.